This invention relates to plastic piping. In one of its aspects this invention relates the joining of plastic piping. In another of its aspects this invention relates to quick coupling of piping. In another of its aspects this invention relates to the fitting of plastic pipe with metal sleeves suitable for use in coupling operations.
The use of plastic pipe has been greatly increased in recent years finding application in many of the uses formerly confined to metal pipe. Plastic pipe now is used for conveying fluids, both gases and liquids, and even for electrical-duct work.
The usual method for joining plastic pipe is by fusing pipe ends together with a fusion machine. A fusion machine has the inherent shortcomings of the necessity of a power source and of being sufficiently bulky that the use of these machines is prohibited in close quarters. Because of these shortcomings, systems have been developed for quick-coupling of plastic pipe.
Among the most advantageous of the quick-coupling methods developed up until now is the coupling set forth in U.S. Pat. No. 3,695,638, utilizing a mechanical clamp-type coupling that keys into circumferential grooves at the end of the pipes to be coupled holding a gasket between the keys and against the abuttment of the coupled pipes. Such a coupling provides a pressure-tight seal and is at the same time resistant to being pulled apart by shrinkage and expansion of the piping.
The present invention provides for adapting plastic pipe with a metal sleeve so that an even more secure coupling can be obtained using a mechanical clamp coupling device of the type set forth in U.S. Pat. No. 3,695,638.
It is therefore an object of this invention to provide plastic pipe adapted for coupling with mechanical clamp-type coupling devices. It is another object of this invention to provide a method for producing pipes adapted for coupling with mechanical clamp-type coupling devices. It is still another object of the invention to provide means for adapting plastic pipe to be coupled with pipes of the other materials of construction.
Other aspects, objects and the various advantages of this invention will become apparent to those skilled in the art upon reading the specification and the appended claims.